After his team was beaten 3-0, Faf du Plessis suggested that India were just so ruthless that whatever they did didn't really matter. And it's true. Virat Kohli's men never let up the pressure on the visitors, but there were still some areas where South Africa could have done a little better.

Prepare for the quicks

Teams touring India know the drill. They send over their A team in advance. They scuff up the practice pitches back home. They go to the UAE on training camps. They hire an Indian batting consultant, or spin consultant.

South Africa prepared hard for the challenge of facing India's spinners, and it showed at various points during the series - the centuries Dean Elgar and Quinton de Kock scored in Visakhapatnam, the fifties by du Plessis and Zubayr Hamza, the dogged lower-order partnerships. R Ashwin and Ravindra Jadeja never once ran through South Africa.

But Mohammed Shami and Umesh Yadav did, repeatedly. They looked unplayable at times, but could South Africa - their top order, in particular - have been more ready for the challenges they posed? They could have, and future teams touring India will no doubt imbibe the lesson South Africa learned the hard way.

Learn from India's quicks

Kagiso Rabada had a pretty decent series, in patches, and his lengths improved with every Test he played, until he delivered a truly outstanding new-ball spell in Ranchi. But he wasn't at the batsmen constantly in the way Shami and Umesh were, nor did he use the bouncer as effectively. And he was the best of South Africa's quicks.

The others were a disappointment. Vernon Philander was accurate, but lost most of his sting after the ball lost its shine, Anrich Nortje was quick but raw, and Lungi Ngidi was disappointingly down on pace in Ranchi after sitting out the first two Tests for fitness reasons.

When they go back home, South Africa will need to figure out why the gap between the two pace attacks became so wide. Do they play too much of their home cricket in overly seam-friendly conditions, and are their quicks at a loss, therefore, when they come across pitches where you need to do a little extra to get any purchase? Should South Africa look into their domestic cricket for fast bowlers who attack the stumps more? Do their seamers need specialised coaching - like their batsmen had on this tour - from a subcontinent expert?

Pick your best specialists

Hamza has a 50-plus first-class average at both provincial and franchise level, and when he got a game in Ranchi, you could see why. There was an effortless simplicity to his batting during his first-innings half-century, with his mind seemingly unclouded by the uncertainty that can strike visiting batsmen in the subcontinent. His defence looked secure, but he was always looking for scoring opportunities, and his control percentage was in the 90s before he paid the price for trying to cut Jadeja off his stumps.

Why didn't Hamza play the first two Tests? South Africa had Theunis de Bruyn at No. 3, and you could see why they wanted to give him a couple of games, he'd scored a century in Sri Lanka from that position. But they also played an allrounder, Senuran Muthusamy, at No. 7.

There was an earnest doggedness to Muthusamy's batting, and he wasn't dismissed in either innings in Visakhapatnam, but he seemed a pretty limited player in comparison to Hamza. More than that, though, what he offered with his left-arm spin was clearly not enough to compensate - he lacked the control to be a viable fifth-bowling option, and there was a half-tracker every two overs that the Indian batsmen ruthlessly put away.

Playing a spin-bowling allrounder is a temptation other touring sides have succumbed to in India. It's a way to hedge your bets. England played Ian Blackwell in Nagpur in 2006 (it was his only Test) and Samit Patel in Ahmedabad six years later. Cameron White is a pretty good batsman, but in his only Test series for Australia, in India in 2008, he played as a spin-bowling allrounder at No. 8.

This idea, of trying to create a credible spin-bowling allrounder out of nowhere, has never worked, but teams keep trying it. Don't do it unless you actually have a Jadeja or a Shakib Al Hasan.

Don't play spinners for the sake of it

This was a lesson South Africa failed to imbibe even after they had learned it the hard way. Dane Piedt played as one of two frontline spinners in Visakhapatnam, and went for 209 runs across the two innings, at 5.81 per over, while only picking up one wicket.

An extra seamer in Visakhapatnam could have given South Africa a little more control, and they seemed to learn from that experience when they went to Pune and played a third seamer. When Keshav Maharaj missed the third Test with a shoulder injury, South Africa could have played four seamers, but instead they left out Philander and went back to Piedt as one of two spinners, and India - Rohit Sharma in particular - toyed with him once again.

Piedt ended the series with the worst economy rate of any bowler in a series in Asia (minimum 200 balls bowled), and South Africa could have been much better served with a seamer bowling all the overs he sent down.

Keep the faith

However awful a tour someone has had, don't jettison the player unless they've clearly shown (like Piedt, maybe) that they may not be that good in the first place. If you've identified someone as a player for the future, and they've shown enough glimpses of that ability, stick with them, and they'll learn from this experience.

Aiden Markram had a nightmarish tour, where he simply couldn't get into double figures, and ended it by breaking his hand lashing out at a "hard object". Maharaj bowled well in patches, but struggled for consistency and ended up with unflattering numbers. These are the kinds of players who could come back to India in 3-4 years' time, and show that they've improved in terms of both skill and mentality.

Elgar and du Plessis have proved this. Both had horror tours of India in 2015, and came into this series with poor records across all their Asia tours, but they both looked a lot better this time around, especially against spin.

Try not to overhaul your coaching staff two months before the next tour

After a disappointing World Cup in which they went out at the group stage, South Africa restructured their entire coaching staff, which meant Ottis Gibson was out after two years in the job, and Enoch Nkwe was in as interim team director.

Nkwe is young and ambitious, and may well go on to have a bright future in the job, but is a tour of India - one of the hardest assignments not just in cricket but in all sport - really the ideal time to bring in a new coach, that too one untested at international level?

It's one thing to throw people in at the deep end, but this was throwing someone in when you could see shark fins poking out of the pool's surface.

Karthik Krishnaswamy is a senior sub-editor at ESPNcricinfo